From a7e0bb5eb661cfde31c383d605cb9cb8ca568bc7 Mon Sep 17 00:00:00 2001
From: Keith Packard <keithp@keithp.com>
Date: Tue, 28 Jun 2016 17:04:59 -0700
Subject: [PATCH] altos: Block interrupts while waking tasks sleeping on
 timers.

Interrupts may not be blocked in the timer ISR, but they need to be
while walking the pending timer list and moving tasks back to the run
queue.

Signed-off-by: Keith Packard <keithp@keithp.com>
---
 src/kernel/ao.h         |  1 +
 src/kernel/ao_task.c    | 15 ++++++++-------
 src/stm/ao_arch_funcs.h |  8 ++++++++
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/kernel/ao.h b/src/kernel/ao.h
index 6ed0299e..27a16606 100644
--- a/src/kernel/ao.h
+++ b/src/kernel/ao.h
@@ -73,6 +73,7 @@ typedef AO_PORT_TYPE ao_port_t;
 #define AO_PANIC_EXTI		16	/* Mis-using exti API */
 #define AO_PANIC_FAST_TIMER	17	/* Mis-using fast timer API */
 #define AO_PANIC_ADC		18	/* Mis-using ADC interface */
+#define AO_PANIC_IRQ		19	/* interrupts not blocked */
 #define AO_PANIC_SELF_TEST_CC1120	0x40 | 1	/* Self test failure */
 #define AO_PANIC_SELF_TEST_HMC5883	0x40 | 2	/* Self test failure */
 #define AO_PANIC_SELF_TEST_MPU6000	0x40 | 3	/* Self test failure */
diff --git a/src/kernel/ao_task.c b/src/kernel/ao_task.c
index e430edc6..03d69caa 100644
--- a/src/kernel/ao_task.c
+++ b/src/kernel/ao_task.c
@@ -165,13 +165,14 @@ ao_task_check_alarm(uint16_t tick)
 {
 	struct ao_task	*alarm, *next;
 
-	ao_list_for_each_entry_safe(alarm, next, &alarm_queue, struct ao_task, alarm_queue) {
-		if ((int16_t) (tick - alarm->alarm) < 0)
-			break;
-		alarm->alarm = 0;
-		ao_task_from_alarm_queue(alarm);
-		ao_task_to_run_queue(alarm);
-	}
+	ao_arch_critical(
+		ao_list_for_each_entry_safe(alarm, next, &alarm_queue, struct ao_task, alarm_queue) {
+			if ((int16_t) (tick - alarm->alarm) < 0)
+				break;
+			alarm->alarm = 0;
+			ao_task_from_alarm_queue(alarm);
+			ao_task_to_run_queue(alarm);
+		});
 }
 
 void
diff --git a/src/stm/ao_arch_funcs.h b/src/stm/ao_arch_funcs.h
index 2c017c79..33359857 100644
--- a/src/stm/ao_arch_funcs.h
+++ b/src/stm/ao_arch_funcs.h
@@ -343,6 +343,14 @@ ao_arch_memory_barrier() {
 	asm volatile("" ::: "memory");
 }
 
+static inline void
+ao_arch_irq_check(void) {
+	uint32_t	primask;
+	asm("mrs %0,primask" : "=&r" (primask));
+	if ((primask & 1) == 0)
+		ao_panic(AO_PANIC_IRQ);
+}
+
 #if HAS_TASK
 static inline void
 ao_arch_init_stack(struct ao_task *task, void *start)
-- 
2.30.2